[Hallicrafters] Orande dip, yellow tubular, and disc ceramic capacitors

[Peter Bertini]

Hi Jim

Ceramic caps are still one of the better choices for RF bypass applications.
ESR measuring instruments generally operate in the subaudible range between
50 and 100kHz, while for most RF applications we are generally more
interested in a cap's bypass effectiveness above 1 MHz and into the UHF
ranges.  ESR is important, but the ESR measurements must be meaningful for
the intended application. This article is far more informative and is more
direct in defining the issues than the link posted earlier:
http://www.atceramics.com/pdf/technotes/capacitor_tol_select.pdf

Golden Ear audio applications aside,  Piezzo effect is a non issue for most
RF applications

There are unlimited examples of commercial two way, broadcast and ham
transmitters and receivers that have sucessfully used ceramic caps for many
applications without problem.

Series resonance measurements can be misleading, basing a cap's merit on
series resonance assumes the capacitor reactances are free of resistive
components. It also doesn't show how effective the capacitor is at bypassing
at other than a single frequency, without an indication of the capacitor's
quality factor. I'd want to see the results based on Q Meter readings. I'd
rather have a cap that has low reactive values at all the frequencies that
need to be bypassed in a given application. I would have to doubt that a
typical ceramic disc is more inductive than the typical spiral wound form
used for most film dielectric capacitors.  If someone could provide accurate
ESR readings for the intended frequencies, it would be informative.

73

Pete
On Sat, Jan 1, 2011 at 5:39 AM, Ross Stenberg <k9cox at charter.net> wrote:

> <
> http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/vaFeedbackFAQ/242F5F2E69DCEC7485256EDF004CA495
> >
>
> > Wow, Ive heard tall tales before and this is right up there.
>
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